Improved determination of particulate absorption from combined filter pad and PSICAM measurements
| Autor: | Rüdiger Röttgers, Derek Connor, Rebecca J. Weeks, Christian Utschig, Kerstin Heymann, Ina Lefering, David McKee |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Materials science
010504 meteorology & atmospheric sciences Scattering business.industry Near-infrared spectroscopy 01 natural sciences Atomic and Molecular Physics and Optics 010309 optics QC350 Wavelength Optics Experimental uncertainty analysis Attenuation coefficient 0103 physical sciences Radiative transfer Transmittance business Absorption (electromagnetic radiation) 0105 earth and related environmental sciences |
| Zdroj: | Lefering, I.; Roettgers, R.; Weeks, R.; Connor, D.; Utschig, C.; Heymann, K.; McKee, D.: Improved determination of particulate absorption from combined filter pad and PSICAM measurements. In: Optics express. Vol. 24 (2016) 22, 24805-24823. (DOI: 10.1364/OE.24.024805) |
| ISSN: | 1094-4087 |
| Popis: | Filter pad light absorption measurements are subject to two major sources of experimental uncertainty: the so-called pathlength amplification factor, β, and scattering offsets, o, for which previous null-correction approaches are limited by recent observations of non-zero absorption in the near infrared (NIR). A new filter pad absorption correction method is presented here which uses linear regression against point-source integrating cavity absorption meter (PSICAM) absorption data to simultaneously resolve both β and the scattering offset. The PSICAM has previously been shown to provide accurate absorption data, even in highly scattering waters. Comparisons of PSICAM and filter pad particulate absorption data reveal linear relationships that vary on a sample by sample basis. This regression approach provides significantly improved agreement with PSICAM data (3.2% RMS%E) than previously published filter pad absorption corrections. Results show that direct transmittance (T-method) filter pad absorption measurements perform effectively at the same level as more complex geometrical configurations based on integrating cavity measurements (IS-method and QFT-ICAM) because the linear regression correction compensates for the sensitivity to scattering errors in the T-method. This approach produces accurate filter pad particulate absorption data for wavelengths in the blue/UV and in the NIR where sensitivity issues with PSICAM measurements limit performance. The combination of the filter pad absorption and PSICAM is therefore recommended for generating full spectral, best quality particulate absorption data as it enables correction of multiple errors sources across both measurements. |
| Databáze: | OpenAIRE |
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